Field of the Invention
The present invention relates to the weight reduction of a seat back for vehicles, and relates to the seat back for vehicles characterized in being excellent in recyclability, fitting feeling, and cushioning properties, in particular.
Description of the Background Art
The seat back for vehicles generally included a metal seat frame or wire, and had an urethane foam used generally as a cushion material, and further had the entire surface thereof covered with a vehicle seat cover. The load of an occupant was supported mainly by deflecting an urethane foam layer interposed between the seat frame or wire and the vehicle seat cover in a compression direction. The cushioning properties and fitting feeling were obtained mainly by reaction force, restoring force, and deflection when the urethane foam layer was deflected in a compression direction.
Furthermore, regarding one technique of the weight reduction of a seat back for vehicles described in Patent Document 1, a seat frame exhibiting a frame shape and having a mountain shape in cross section had an inclined surface corresponding to one side of such a mountain shape at an inner periphery of the frame shape as well as facing a seated person. The seat frame was covered with a net having elasticity whose peripheral portion was drawn over the top of the mountain shape and fixed on the other side of the mountain shape so as to form a seating surface having a concave surface shape. An angle was provided between the net and the inclined surface of the seat frame.
Regarding another technique of the weight reduction described in Patent Document 2, a seat for vehicles included a seating portion having a base plate arranged on a seat frame in an attachable and detachable fashion, a block arranged on the base plate, a spring plate arranged on the block, and a vehicle seat cover covering the spring plate. The block was arranged to form a predetermined space between the base plate and the spring plate. The spring plate was formed of a foam having elasticity made of any of a PP (polypropylene) bead foam, a PE (polyethylene) bead foam, a PP foam; a PE foam, an AS resin (acrylonitrile/styrene resin) foam, EVA (ethylene-vinyl acetate copolymer resin), and an urethane foam material, and the spring plate was deflected to the predetermined space when force in a direction toward the base plate was applied.